/*
 * Copyright (c) 2011-2012 Alexander Dubu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * o  Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * o  Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * o  Neither the name Axil nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package axil.stdlib.core.function;

import axil.api.AxilObject;
import axil.api.extend.Environment;
import axil.api.extend.Function;
import axil.api.extend.Parameters;
import axil.api.extend.Source;
import axil.stdlib.core.type.Nil;

import static axil.framework.Functions.iter;


/**
 * A variable argument function that returns the minimum element from a set of
 * variable arguments. For example:
 *
 * 		min(3, 5, 7, 9)
 *
 * If a single value is specified, then that value is assumed to be a list and
 * the smallest value from that list is returned. For example:
 *
 * 		min(list(5, 6, 7, 8))
 */
public class Min implements Function {
	/**
	 * Execute this function with the given arguments. The Axil compiler will
	 * ensure that the number of arguments passed to the function are valid.
	 * If this function fails during execution for any reason, then an exception
	 * is thrown.
	 */
	public AxilObject eval(Environment env, Parameters params, Source source) {
		final int size = params.size();
		switch(size) {
		case 0:
			return Nil.object;

		case 1:
			AxilObject min = Nil.object;
			AxilObject a = params.a();
			if (a instanceof Iterable) {
				for (AxilObject o : iter(params.a())) {
					if (min == Nil.object) {
						min = o;
					} else {
						if (o.comparedTo(min) < 0) {
							min = o;
						}
					}
				}
			} else {
				min = a;
			}
			return min;

		default:
			AxilObject m = params.a();
			for (int i = 1; i < size; i++) {
				AxilObject o = params.at(i);
				if (o.comparedTo(m) < 0) {
					m = o;
				}
			}
			return m;
		}
	}
}
